The present invention relates to a cable mounting method and mounting devices used therewith, and refers more particularly to a method and mounting means used for securely but readily removable mounting of cables and instrumentation carried by cables, in environments wherein fluid flow may induce flow vibrations in the structures to which the cables are secured, said fluid flow also imposing like vibration effect and other load burden on the mountings as such.
Certain operating systems and components are required to be subjected to Flow Induced Vibration (FIV) testing. For example, Nuclear Regulatory Commission regulations mandate this for prototype nuclear reactors. For execution of this required testing, various instrumentation and devices must be installed in the reactor at key locations and on key reactor components. Such devices include strain gages, accelerometers, test leads, sensors and the like, with their installation including use and presence of cables connected with the devices so that data reflecting various parameters of conditions within the reactor during the testing can be detected and recorded.
Testing in the case of a reactor will involve study of flow conditions at partial load, criticality and normal power reactor operating conditions. The flow conditions existing in the reactor may produce effects on reactor internal components, inducement of vibration in the components being of prime interest. Cable and instrument mountings also are exposed to the effects of the highly pressurized flow within the reactor and are subjected to flow induced vibration as well.
Installation of the instrumentation and cables in the reactor must be in such a manner that these elements readily withstand the vibration loading and any other force imposed on them by the fluid flow generated in the reactor so that the elements remain positioned where intended, mounted to function with reliability and accuracy during testing, and readily and conveniently removed from the reactor on conclusion of testing if required.
The conventional manner of securing cables in the reactor involves attaching them to a reactor support surface with clips tack welded to the support surface every few inches of cable run. The clips have a part-circular midpart which fits over the cable, and flat side parts extending at each side of the midpart. The side parts are tack welded to the support surface.
To remove a clip, the cable is pulled to separate the clip, a loose end of one side part is generally grasped with pliers and that side pulled or worked loose from the support surface, followed by pulling loose of the other side part while holding the first removed side part tightly with the pliers. A disadvantage of this arrangement is that the cable easily separates from the clip on removal and while the clip may still be held, the cable can drop inside the reactor and instrumentation connected thereto can be damaged. It is also possible that the clip separated from the cable can be dropped in the reactor to a relatively inaccessible location creating a burdensome task to find and retrieve the clip.
An alternative removal involves simply pulling on the cable to tear away or shear the clip midpart so the cable can be freed, the clip being left in place within the reactor. This procedure has the disadvantage of possible cable damage, and potential for loose clip residue within the reactor.
It is desirable that FIV test requirements as same relate to mounting of instrumentation, be better met in regard to testing of advanced reactor designs, with a more reliable, sure and simplified method of effecting such mountings and with mounting devices that eliminate the disadvantages of prior practice enumerated above.